Method and apparatus for transmitting and receiving data in a communication system using beamforming

ABSTRACT

A method and apparatus for transmitting and receiving data in a communication system using beamforming are provided. The transmission method includes transmitting a control channel signal in a control channel region of a subframe using a first transmission beam of a base station. The transmission method also includes transmitting a data signal during a predetermined time period of a data region after the control channel region in the subframe using a second transmission beam determined based on the first transmission beam. The transmission method further includes transmitting a data signal in a remaining data region following the predetermined time period using a scheduled transmission beam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/858,228, filed on Apr. 24, 2020, which is a continuation of U.S.patent application Ser. No. 15/985,434, filed on May 21, 2018, now U.S.Pat. No. 10,637,627, which is a continuation of U.S. patent applicationSer. No. 14/326,405, filed on Jul. 8, 2014, now U.S. Pat. No.10,003,446, which is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2013-0079561, filed Jul. 8, 2013, inthe Korean Intellectual Property Office, the disclosures of which areherein incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus fortransmitting and receiving data, taking into account a decoding latencyof a mobile station in a communication system using beamforming.

BACKGROUND

In order to satisfy ever-increasing demands for wireless data traffic,wireless communication systems can be developed toward higher datarates. A wireless communication system that focuses on the increase ofspectral efficiency to increase data rate is under development. However,the increase of spectral efficiency may not suffice to satisfy thesoaring demands for wireless data traffic.

SUMMARY

To address the above-discussed deficiencies, it is a primary object toprovide a method and apparatus for transmitting and receiving signals ina communication system.

In an first example, a method and apparatus are provided fortransmitting and receiving data, taking into account a latency withwhich a mobile station decodes a scheduling assignment channel in acommunication system using beamforming.

In a second example, a method and apparatus are provided fortransmitting and receiving data, taking into account a latency withwhich a mobile station decodes a scheduling assignment channel, when themobile station uses Reception (Rx) beamforming.

In a third example, a method is provided for transmitting data in acommunication system using beamforming. The method includes transmittinga control channel signal in a control channel region of a subframe usinga first transmission beam of a base station. The method also includestransmitting a data signal during a predetermined time period of a dataregion after the control channel region in the subframe using a secondtransmission beam determined based on the first transmission beam. Themethod further includes transmitting a data signal in a remaining dataregion following the predetermined time period using a scheduledtransmission beam.

In a fourth example, a method is provided for receiving data in acommunication system using beamforming. The method includes receiving acontrol channel signal in a control channel region of a subframe using afirst reception beam of a mobile station. The method also includesreceiving a data signal during a predetermined time period of a dataregion after the control channel region in the subframe using the firstreception beam. The method further includes receiving a data signal in aremaining data region following the predetermined time period using areception beam determined according to the control channel signal.

In a fifth example, a method is provided for transmitting data in acommunication system using beamforming. The method includes generatingone or more control channel elements to be transmitted in a controlchannel region of a subframe. The method also includes determining afirst transmission beam to be used for transmission of the controlchannel elements. The method further includes generating data burstscorresponding to the control channel elements. The method includesdetermining to use a second transmission beam determined according tothe first transmission beam, if a time gap between an encoding unitincluding a first control channel element among the control channelelements and a first data burst corresponding to the first controlchannel element among the data bursts is shorter than a predeterminedwindow size. The method also includes transmitting a control channelsignal including the control channel elements in the control channelregion using the first transmission beam. The method further includestransmitting a first data signal carrying the first data burst in a dataregion following the control channel region in the subframe using thesecond transmission beam.

In a sixth example, a method is provided for receiving data in acommunication system using beamforming. The method includes receiving acontrol channel signal in a control channel region of a subframe using afirst reception beam. The method also includes detecting a first controlchannel element allocated to a mobile station from the control channelsignal. The method further includes receiving a data signal during apredetermined time period after the control channel region using thefirst reception beam.

In a seventh example, an apparatus is provided for transmitting data ina communication system using beamforming. The apparatus includes atransmitter configured to transmit a control channel signal in a controlchannel region of a subframe using a first transmission beam of a basestation. The transmitter is also configured to transmit a data signalduring a predetermined time period of a data region after the controlchannel region in the subframe using a second transmission beamdetermined based on the first transmission beam. The transmitter isfurther configured to transmit a data signal in a remaining data regionfollowing the predetermined time period using a scheduled transmissionbeam. The apparatus also includes a controller configured to controltransmission beamforming of the transmitter.

In an eighth example, an apparatus is provided for receiving data in acommunication system using beamforming. The apparatus includes areceiver configured to receive a control channel signal in a controlchannel region of a subframe using a first reception beam of a mobilestation The receiver is also configured to receive a data signal duringa predetermined time period of a data region after the control channelregion in the subframe using the first reception beam. The receiver isfurther configure to receive a data signal in a remaining data regionfollowing the predetermined time period using a reception beamdetermined according to the control channel signal. The apparatus alsoincludes a controller configured to control reception beamforming of thereceiver.

In an ninth example, an apparatus is provided for transmitting data in acommunication system using beamforming. The apparatus includes acontroller configured to generate one or more control channel elementsto be transmitted in a control channel region of a subframe. Thecontroller is also configured to determine a first transmission beam tobe used for transmission of the control channel elements. The controlleris further configured to generate data bursts corresponding to thecontrol channel elements. The controller is configured to use a secondtransmission beam determined according to the first transmission beam,if a time gap between an encoding unit including a first control channelelement among the control channel elements and a first data burstcorresponding to the first control channel element among the data burstsis shorter than a predetermined window size. The apparatus also includesa transmitter configured to transmit a control channel signal includingthe control channel elements in the control channel region using thefirst transmission beam. The apparatus is also configured to transmit afirst data signal carrying the first data burst in a data regionfollowing the control channel region in the subframe using the secondtransmission beam.

In a tenth example, an apparatus is provided for receiving data in acommunication system using beamforming. The apparatus includes areceiver configured to receive a control channel signal in a controlchannel region of a subframe using a first reception beam. The receiveris also configured to receive a data signal during a predetermined timeperiod after the control channel region using the first reception beam.The apparatus also includes a controller configured to control receptionbeamforming of the receiver.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the disclosure.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example of transmitting and receiving signals bybeamforming according to this disclosure;

FIG. 2 illustrates an example beamforming-based communication between abase station and a mobile station according to this disclosure;

FIG. 3 illustrates an example problem that may be encountered with thetransmission sequence of a control channel and data according to thisdisclosure;

FIG. 4 illustrates an example transmission sequence of a control channeland data according to this disclosure;

FIG. 5 illustrates an example transmission sequence of a control channeland data according to this disclosure;

FIG. 6 illustrates an example subsframe structure in which a periodicsignal is interposed between a control channel and data according tothis disclosure;

FIG. 7 illustrates an example subsframe structure in which a data burstindicated by a control channel is disposed in a next subframe accordingto this disclosure;

FIG. 8 illustrates an example subsframe structure in which the sameReception (Rx) beam is applied to a control channel and a data regionfollowing the control channel according to this disclosure;

FIG. 9 is an example flowchart illustrating an operation of a basestation according to this disclosure;

FIG. 10 is an example flowchart illustrating an operation of a mobilestation according to this disclosure;

FIGS. 11A and 11B illustrate an example subframe structure for a casewhere a transmission scheme is determined for a data region according toa time gap between a control channel and the data region according tothis disclosure;

FIG. 12 is an example flowchart illustrating an operation of a basestation according to this disclosure;

FIG. 13 is a flowchart illustrating an operation of a mobile stationaccording this disclosure;

FIG. 14 is an example block diagram of a base station according to thisdisclosure; and

FIG. 15 is an example block diagram of a mobile station according tothis disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

FIGS. 1 through 15, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged electronic device. The followingdescription with reference to the accompanying drawings is provided toassist in a comprehensive understanding of exemplary embodiments of thedisclosure as defined by the claims and their equivalents. It includesvarious specific details to assist in that understanding but these areto be regarded as merely exemplary. Accordingly, those of ordinaryskilled in the art will recognize that various changes and modificationsof the embodiments described herein can be made without departing fromthe scope and spirit of the disclosure. In addition, descriptions ofwell-known functions and constructions may be omitted for clarity andconciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments is providedfor illustration purpose only and not for the purpose of limiting thedisclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to those ofskill in the art, may occur in amounts that do not preclude the effectthe characteristic was intended to provide.

A technique to satisfy the demands for wireless data traffic can be touse a very broad frequency band. Legacy cellular mobile communicationsystems can use frequency bands of 10 GHz or below and can havedifficulty in securing a broad frequency band. Accordingly, there is aneed for securing a broadband frequency in a higher frequency band toincrease data capacity.

However, as wireless communication is conducted in a higher frequency,the wireless communication can suffer from more propagation path loss.The resulting decrease in a propagation distance can reduce servicecoverage. One of major techniques that can mitigate propagation pathloss and can prevent reduction of propagation distances is beamforming.

There can be Transmission (Tx) beamforming at a transmitter andReception (Rx) beamforming at a receiver. Tx beamforming can improvedirectivity by steering signals in a specific direction and thus to aspecific propagation area through a plurality of antennas. A set ofantennas can be referred as an antenna array and each antenna of theantenna array can be referred to as an array element. Variousconfigurations can be available to an antenna array, such as of lineararray, planar array, and the like. Due to its improved directivity, Txbeamforming can increase a propagation distance. Further, since almostno signal is transmitted in directions other than an intended direction,signal interference with other receivers can be reduced. A receiver canperform beamforming on received signals through an Rx antenna array. Rxbeamforming can increase the reception sensitivity of a signal from anintended direction by steering Rx beams in the direction, whileexcluding signals received from the other directions. Therefore, Rxbeamforming can offer the gain of blocking interference signals.

As described above, in order to achieve a broad frequency band, theintroduction of an extremely high frequency system, namely, a MilliMeterWave (MMW) system can be expected and beamforming can be underconsideration for the MMW system to overcome propagation path loss.

An extremely high frequency wireless communication system usingbeamforming can adopt beamforming for DownLink (DL) reception as well asDL transmission in order to overcome much propagation loss and muchpenetration loss inherent to the channel propagation property of anextremely high frequency band.

FIG. 1 illustrates an example of transmitting and receiving signals bybeamforming according to this disclosure.

Referring to FIG. 1, a Base Station (BS) 100 can cover a service areaincluding one cell 10 divided into a plurality of sectors 20. The numberof sectors in the cell 10 can vary. The BS 100 can use multiple beamsper sector 20. To achieve a beamforming gain and support one or moreMobile Stations (MSs), the BS 100 can form one or more DL/UpLink (UL)Transmission (Tx)/Reception (Rx) beams by sweeping the Tx/Rx beams indifferent directions simultaneously or sequentially.

For example, the BS 100 can simultaneously form N Rx beams in Ndirections during the duration of N slots. In an embodiment, the BS 100can sequentially form N Rx beams in N directions by sweeping the N Rxbeams during the duration of N slots. Specifically, a first Rx beam canbe formed only in a first slot, a second Rx beam can be formed only in asecond slot, and an N^(th) Rx beam can be formed only in an N^(th) slot.

Due to its structural constraints, an MS 110 can generally be configuredto use a wide beamwidth supporting a small beam gain, compared to the BS100. The MS 110 can support one or more Rx/Tx beams for DL/UL dependingon the configuration of the MS 110.

DL beamforming can be implemented by Tx beamforming of a BS or acombination of Tx beamforming of a BS and Rx beamforming of an MS. DLbeamforming can use a DL beam tracking procedure in which a best Tx-Rxbeam pair is selected from among possible beam pairs that could beproduced from one or more BS Tx beams and one or more MS Rx beamssteered in a plurality of directions depending on the structures of anMS and a BS and both the MS and the BS can acquire information about thebest Tx-Rx beam pair. A predetermined DL Reference Signal (RS) can beused for the DL beam tracking.

FIG. 2 illustrates an example beamforming-based communication between aBS and an MS according to this disclosure. In FIG. 2, a BS 200 can usesa plurality of Tx/Rx beams 202 steered in different directions on DL/ULin one sector and each of MSs 210, 220, and 230 can support one or moreTx/Rx beams.

Referring to FIG. 2, the BS 200 can simultaneously transmit a pluralityof beamformed signals (such as Tx beams) in different directions or cantransmit a plurality of signals in Tx beams steered in differentdirections by sweeping the Tx beams sequentially in time, one or more Txbeams at each time, as indicated by reference numeral 211.

To achieve a maximum beamforming gain under constraints imposed by theconfigurations and complexity of the MSs 210, 220, and 230, the MSs 210,220, and 230 can support omnidirectional reception without supporting Rxbeamforming, receive signals in only one specific beamforming pattern ateach time, while supporting Rx beamforming, or can receive signals bysimultaneously applying a plurality of Rx beamforming patterns indifferent directions, while supporting Rx beamforming.

Each of the MSs 210, 220, and 230 can select a best Tx beam from among aplurality of Tx beams from the BS 200 based on a measurement result ofthe channel quality of a DL RS for each Tx beam and can feed backinformation about the best Tx beam to the BS 200. Then the BS 200 cantransmit a specific signal to the MS in a selected best Tx beam for theMS. Each MS supporting Rx beamforming can measures the channel qualityof each Tx-Rx beam pair in relation to a plurality of Rx beams of theMS, can select and manage one or a predetermined number of best beampairs or all beam pairs, can report the selected best beam pair(s) tothe BS 200, and can receive a signal from the BS 200 in an appropriatebeam pair according to a situation.

In the case of multiple accesses of the MSs 210, 220, and 230 to the BS200, the BS 200 can indicate a resource allocation for data transmissionto each of the MSs 210, 220, and 230 on a specific control channel. Inan embodiment, the control channel indicating allocated resources toeach of the MSs 210, 220, and 230 can be referred to as a schedulingassignment channel or a Physical Downlink Control Channel (PDCCH). Ascheduling assignment channel and data can be multiplexed in TimeDivision Multiplexing (TDM) in a subframe being a transmission timeunit. In an embodiment, a subframe and a scheduling period can be thesame transmission unit.

In a system using Rx analog beamforming, a receiver (an MS in the caseof DL transmission) can select an appropriate Rx beam before datareception and receive data in the selected Rx beam at a data receptiontime. An Rx beam appropriate for data reception can vary depending on aTx beam or a Multiple Input Multiple Output (MIMO) transmission modeselected by a transmitter (a BS in the case of DL transmission).Accordingly, the BS can transmit information about the Tx beam or MIMOtransmission mode selected for data transmission to the MS on a controlchannel before the data transmission.

FIG. 3 illustrates an example problem that can be encountered with thetransmission sequence of a control channel and data according to thisdisclosure.

Referring to FIG. 3, data 320 can be transmitted shortly after a controlchannel, PDCCH 310 in one time unit. An MS can acquire schedulinginformation such as information about a Tx beam and a MIMO transmissionmode that a BS has selected for transmission of the data 320 byreceiving and decoding a signal on the PDCCH 310. Before transmittingthe PDCCH 310, the BS can determine the Tx beam (for example, a best Txbeam) to be used for transmission of the PDCCH 310 and can explicitly orimplicitly signal the determined Tx beam to the MS. The Tx beam to beused for transmission of the PDCCH 310 can be determined, for example,based on a best Rx beam selected by the MS. Before receiving the PDCCH310, the MS can acquire information about the Tx beam of the BS and anRx beam of the MS to be applied for reception of the PDCCH 310. In anembodiment, the MS can determine a best Tx beam of the BS by a beamtracking procedure, report the best Tx beam to the BS, determine a bestRx beam matching to the best Tx beam, and decide to use the best Rx beamfor reception of the PDCCH 310.

If the MS has a plurality of Rx RF paths, that is, a plurality of Rxchains, the MS can receive the PDCCH 310 in a plurality of Rx beams. Inthis case, the BS can select a predetermined number of Tx beams in adescending order of signal strengths or Signal to Interference and NoiseRatios (SINRs) from among M best Tx beams (M is an integer largerthan 1) reported as a feedback by the MS and can use the selected Txbeams in transmitting the PDCCH 310. The BS can select up to M Tx beamsand can use one or more of the selected Tx beams simultaneously intransmitting the PDCCH 310. The number of Tx beams to be used for PDCCHtransmission can be agreed between the MS and the BS during negotiationsor preset by a system operator or a communication standard.

A specific decoding latency, interval-L 315 can be taken for the MS todecode the PDCCH 310. Particularly in the case of Rx analog beamforming,if the MS does not have knowledge of a Tx beam selected by the BS, theMS may not accurately set Rx beam weights for reception of a datasignal. As a result, the MS may not receive a signal carrying the data320 successfully during the interval-L 315. The MS can receive anddecode the signal carrying the data 320 successfully, starting from atime 325 at which the interval-L 315 ends and the PDCCH 310 can becompletely decoded. Therefore, the MS can face the problem of signalloss during the interval-L 315.

FIG. 4 illustrates an example transmission sequence of a control channeland data according to this disclosure.

Referring to FIG. 4, a PDCCH region 410 can include a plurality of PDCCHelements and a data region 420 can include a plurality of data bursts ina subframe 400 being a transmission time unit. The PDCCH elements of thePDCCH region 410 can be transmitted in at least one Tx beam agreedbetween a BS and an MS, and the data bursts of the data region 420 canbe transmitted in Tx beams independently determined by data scheduling.In an embodiment, the BS can transmit at least one data packet of arelatively small size in the PDCCH region 410. That is, if the PDCCHregion 410 has a remaining space large enough to carry data, the PDCCHregion 410 can carry the data. The same or similar Tx beam and MIMOtransmission mode as or to used for the PDCCH elements can apply to thedata carried in the PDCCH region 410.

Each PDCCH element 405 can indicate a specific data burst 425 in thedata region 420 and can deliver scheduling information such asinformation about a Tx beam and/or a MIMO transmission mode used fortransmission of the specific data burst 425. The PDCCH element 405 canprecede the data burst 425 by a specific time gap 415 or longer. Thetime gap 415 can be longer than a time required for PDCCH decoding (thatis, the interval-L) at the MS. After decoding the PDCCH element 405allocated to the MS in the PDCCH region 410, the MS can receive the databurst 425 indicated by the PDCCH element 405 based on schedulinginformation extracted from the PDCCH element 405 using an accurate Rxanalog beam. The PDCCH elements of the PDCCH region 410 can beseparately or jointly encoded prior to transmission. If the PDCCHelements are separately encoded, each PDCCH element can be one encodingunit. On the other hand, if the PDCCH elements are jointly encoded, theplurality of PDCCH elements can form one encoding unit. The encodingunit can be disposed before data bursts corresponding to the encodingunit by the interval-L or longer. An encoding unit can refer to datainput to an encoder at one time in a transmitter.

To support the channel structure illustrated in FIG. 4, the BS canschedule each PDCCH element 405 of the PDCCH region 410 to be locatedapart from a data burst indicated by the PDCCH element 405 by the timegap 415 or longer. Consequently, data scheduling can be limited andscheduling complexity can be increased. For example, although a specificdata burst can be allocated first with priority and thus can be locatedat the start of a subframe, a PDCCH element associated with the databurst can be located almost at the end of the PDCCH region 410 accordingto a Tx analog beam area. To avoid this case, scheduling complexity canbe significantly increased.

FIG. 5 illustrates an example transmission sequence of a control channeland data according to this disclosure.

Referring to FIG. 5, a PDCCH region 510 can include a PDCCH element 505and a data burst 525 indicated by the PDCCH element 505 can be locatedin a data region 520. As disclosed herein, the PDCCH region 510 canselectively include a data packet(s) of a small size. If the duration ofthe PDCCH region 510 is short, even though a time gap between the PDCCHelement 505 and the data burst 525 is set to be longer than a PDCCHdecoding latency 515 by BS scheduling, time and frequency resources canbe wasted, as illustrated in FIG. 5.

FIG. 6 illustrates an example subsframe structure in which a periodicsignal is interposed between a control channel and data according tothis disclosure.

Referring to FIG. 6, a PDCCH region 610 can include a plurality of PDCCHelements and a data region 620 can include a plurality of data bursts ina subframe 600. As disclosed herein, the PDCCH region 610 canselectively include a data packet(s) of a small size. Each PDCCH element605 can include scheduling information related to a specific data burst625 of the data region 620.

A preset periodic signal 630 can shortly follow the PDCCH region 610,before the data region 620. The periodic signal 630 can preferably havea periodicity equal to or shorter than a data scheduling period, like anRS. In an embodiment, the periodic signal 630 can be transmitted duringa time period at least longer than a PDCCH decoding latency 615 of anMS. The PDCCH decoding latency 615 of the MS can be predicted based onthe capabilities of the MS by a BS or can be set in compliance with asystem standard.

The size of the PDCCH region 610 can be changed in each subframe. Theposition of resources carrying the periodic signal 630 can also bechanged in each subframe. Therefore, the BS can provide the contents ofinformation included in the periodic signal 630 and an indicationindicating whether the periodic signal 630 is used or not to the MS at atime before the PDCCH region 610 in the same subframe 600. The MS canreceive the periodic signal 630 successfully after the PDCCH region 610based on the indication. For example, if the periodic signal 630includes an RS, the MS can measure a signal strength using the periodicsignal 630. The periodic signal 630 can be broadcast, multicast, orunicast.

FIG. 7 illustrates an example subsframe structure in which a data burstindicated by a control channel is disposed in a next subframe accordingto this disclosure.

Referring to FIG. 7, first and second subframes 700 a and 700 b canstart with PDCCH regions 710 a and 710 b, respectively. The PDCCH region710 a can deliver PDCCH signals carrying scheduling information aboutdata transmitted in resource areas 720 a and 720 b that span from a timeS to a time E. As disclosed herein, the PDCCH region 710 a canselectively include a data packet(s) of a small size. The time S can bea predetermined time interval TL 715 after the end of the PDCCH region710 a and the time E can be the predetermined time interval TL 715 afterthe end of the PDCCH region 710 b. The length of the time interval TL715 can be preset or signaled by the BS.

The PDCCH region 710 a of the first subframe 700 a can include logicalresource indexes starting with logical resource index 0 indicating aresource at the time S in the first subframe 700 a and ending with alogical resource index indicating a resource at the time E in the nextsubframe 700 b. The PDCCH region 710 b between the time S and the time Emay not be considered in calculating the logical resource indexesindicated by the PDCCH region 710 a. The BS can transmit data signals inindependently scheduled Tx beams in the data regions 720 a and 720 birrespective of a Tx beam used for the PDCCH region 710 a. The datasignals can include data bursts indicated by PDCCH elements of the PDCCHregion 710 a.

The MS can determine the logical resource indexes indicated by the PDCCHregion 710 a by excluding a resource area corresponding to the PDCCHregion 710 b. If the PDCCH region 710 b is located between the dataregions 720 a and 720 b, the MS can monitor and receive a signal in thePDCCH region 710 b in an Rx beam suitable for a PDCCH and can continueto receive data in the following data region 720 b based on schedulinginformation indicated by the PDCCH region 710 a.

FIG. 8 illustrates an example subsframe structure in which the same Rxbeam is applied to a control channel and a data region following thecontrol channel according to this disclosure.

Referring to FIG. 8, a subframe can start with a PDCCH region 810 and aBS can transmit a data signal in a data region 820 spanning a timeinterval TL 815 from the end of the PDCCH region 810, using the same ora similar beam as or to a beam used for the PDCCH region 810. Thesimilar beam can be, for example, a beam adjacent to the Tx beam usedfor the PDCCH region 810. An MS can report information about at leastone best Tx beam paired with a best Rx beam of the MS to the BS and theBS can determine a BS Tx beam for use in the data region 820 based onthe reported information.

The MS can receive the data signal during the time interval T_(L) 815from the end of the PDCCH region 810 using the same Rx beam as for thePDCCH region 810. After the time interval T_(L) 815, the MS can receivea data signal using an Rx beam acquired by decoding the PDCCH region810.

The length of the time interval T_(L) 815 can be agreed between the BSand the MS, indicated through broadcasting by the BS from among aplurality of values preset between the BS and the MS, or signaled by theBS.

In an embodiment, if the BS allocates data to the resource area 820including the time interval T_(L) 815 after the PDCCH region 810, the MScan receive the data in the resource area 820 using the same Rx beam asapplied to the PDCCH region 810, the BS can determine a Tx beam and/or aMIMO transmission mode for transmission of the data in the resource area820. In an embodiment, the BS can transmit data in the resource area 820using the same Tx beam or MIMO transmission mode as applied to the PDCCHregion 810. In an embodiment, the BS can transmit data in the resourcearea 820 using a Tx beam adjacent to a Tx beam applied to the PDCCHregion 810, so that the MS can receive the data successfully in theresource area 820 using the same Rx beam as in the PDCCH region 810. TheBS can use information reported by the MS in determining a Tx beam foruse in the resource area 820. The information can indicate at least onebest BS Tx beam paired with an Rx beam that the MS uses in the PDCCHregion 810. The information can be determined in the MS by a beamtracking procedure.

For data transmission after the time interval T_(L) 815, the BS can usea Tx beam and/or a MIMO transmission mode determined by scheduling,independently of a Tx beam applied to the PDCCH region 810.

FIG. 9 is an example flowchart illustrating an operation of a BSaccording to this disclosure. The operation of FIG. 9 can support thechannel structure illustrated in FIG. 8.

Referring to FIG. 9, the BS can broadcast information about the lengthof a time period during which an Rx beam of an MS is not changed,following a PDCCH region, that is, the length of a time interval T_(L)to MSs within a cell covered by the BS in operation 905. In operation910, the BS can schedule a resource area including at least the timeinterval T_(L) following the PDCCH region. The BS can determine data tobe transmitted in the resource area and a transmission scheme fortransmission of the determined data, specifically, a BS Tx beam and/or aMIMO transmission mode by the scheduling. In operation 915, the BS cantransmit a PDCCH signal in a first Tx beam and/or a first MIMOtransmission mode in the PDCCH region and can transmit the scheduleddata during the time interval T_(L) following the PDCCH region using thefirst Tx beam and/or the first MIMO transmission mode. The first Tx beamand/or the first MIMO transmission mode can be determined for PDCCHtransmission. The BS can transmit a data signal using a Tx beam and/orMIMO transmission mode scheduled for the data after the time intervalT_(L).

FIG. 10 is an example flowchart illustrating an operation of an MSaccording to this disclosure. The operation of FIG. 10 can support thechannel structure illustrated in FIG. 8.

Referring to FIG. 10, the MS can receive, from a BS, information aboutthe length of a time period during which the MS does not need to changean Rx beam, following a PDCCH region, that is, information about thelength of a time interval TL in operation 1005. In operation 1010, theMS can monitor a PDCCH signal using a first Rx beam determined for PDCCHreception in the PDCCH region from the start of a subframe. The first Rxbeam can be selected from among a plurality of Rx beams of the MS inconsideration of a first Tx beam and/or a first MIMO transmission modethat the BS uses for PDCCH transmission.

In operation 1015, the MS can receive a data signal using the first Rxbeam during the time interval T_(L) shortly after the PDCCH region andcan interpret the data signal based on the same transmission scheme asused for the PDCCH. The MS can receive a data signal based on a Tx beamand/or a MIMO transmission mode indicated by a PDCCH associated withdata in a data region following the time interval T_(L).

FIGS. 11A and 11B illustrate an example subframe structure for a casewhere a transmission scheme is determined for a data region according toa time gap between a control channel and the data region according tothis disclosure.

Referring to FIG. 11A, a subframe can starts with a PDCCH region 1110.The PDCCH region 1110 can include a plurality of PDCCH elements and adata region 1120 following the PDCCH region 1110 can include a pluralityof data bursts indicated respectively by the PDCCH elements.

If a time gap between a specific PDCCH element 1105 of the PDCCH region1110 and a starting data burst 1125 of the data region 1100 indicated bythe PDCCH element 1105 is shorter than a predetermined time intervalT_(L) 1115, the BS can transmit a data signal using the same (orsimilar) Tx beam and/or MIMO transmission mode as (or to) used for thePDCCH region 1110 during the time interval T_(L) 1115 after the PDCCHelement 1105. An MS can receive the data signal using the same (orsimilar) Rx beam from the start of the PDCCH element 1105 to the end ofthe time interval T_(L) 1115.

If the MS fails to detect a PDCCH element that allocates data to the MSuntil after the PDCCH region 1110 is completely decoded, the MS can endthe reception operation in the current subframe.

In an embodiment, if the PDCCH elements of the PDCCH region 1110 arejointly encoded, the BS can transmit a data signal using the same (orsimilar) Tx beam and/or MIMO transmission mode as (or to) in the PDCCHregion 1110 during the time interval T_(L) after the encoding unit (thatis, the jointly coded PDCCH elements). Then the MS can decode the wholejointly coded PDCCH elements and can receive a data signal using thesame (or similar) Rx beam as (or to) used for the PDCCH region 1110during at least the time interval T_(L) after the PDCCH region 1110.

If the MS succeeds in decoding the PDCCH element 1105 allocated to theMS earlier than the end of the PDCCH region 1110 by the time intervalT_(L), the MS can set a best Rx beam for the data region 1125 indicatedby the PDCCH element 1105, taking into account a Tx beam or a MIMOtransmission mode indicated by the PDCCH element 1105. In this case, thebest Rx beam can be set independently of a Tx beam or a MIMOtransmission mode applied to the PDCCH region 1110.

In an embodiment, the MS can receive a data signal using the same Rxbeam as used for the PDCCH region 1110 during the time interval T_(L)after the PDCCH region 1110 irrespective of when the MS has detected thePDCCH element allocated to the MS.

If a time gap between a PDCCH element allocated to the MS and a databurst indicated by the PDCCH element is shorter than the time intervalT_(L), the MS can receive the data burst using the same Rx beam as forPDCCH reception, the BS can select a Tx beam and/or a MIMO transmissionmode for transmission of the data burst. In an embodiment, the BS cantransmit data using the same Tx beam or MIMO transmission mode as usedfor PDCCH transmission during the time interval T_(L) after the PDCCHregion 1110.

Referring to FIG. 11B, the BS can transmit two (or more) PDCCH elements1105 a and 1105 b allocated to the MS in the PDCCH region. Upon receiptof the data region 1120, the MS can receive a first data burst 1125 aindicated by the decoded first PDCCH element 1105 a using an Rx beamsuitable for reception of the first data burst 1125 a. The first databurst 1125 a can reside within the time interval T_(L) 1115 after thestart of the second PDCCH element 1105 b. Since a second data burst 1125b does not fall into the time interval T_(L) 1115 after the PDCCH region110, the MS can receive the second data burst using an Rx beamdetermined based on a transmission scheme indicated by the second PDCCHelement 1105 b.

FIG. 12 is an example flowchart illustrating an operation of a BSaccording to this disclosure. The operation can support the channelstructure illustrated in FIGS. 11A and 11B.

Referring to FIG. 12, the BS can broadcast information about the lengthof a time interval during which an MS Rx beam is not changed after aPDCCH region, that is, information about the length of a time intervalT_(L) to MSs within a cell covered by the BS by system information inoperation 1205. In operation 1210, the BS can determine data to betransmitted in at least one subframe and can decide to perform datascheduling to determine transmission schemes for the determined data.For example, the data scheduling can be performed at the start of eachsubframe. The BS can determine at least one data burst to be transmittedand a PDCCH element indicating each data burst and arranges the PDCCHelements in a PDCCH region in an appropriate order during thescheduling. The BS can arrange the plurality of PDCCH elements invarious orders of MS Identifiers (IDs), BS Tx beams, MS Rx beams, datatypes, and the like. The BS can encode the PDCCH elements separately orjointly. The BS can arrange the at least one scheduled data burst in adata region in an appropriate order.

In operation 1215, the BS can compare a time gap between a specificPDCCH element (hereinafter, referred to as a first PDCCH element) and adata burst (hereinafter, referred to as a first data burst) indicated bythe first PDCCH element with the time interval T_(L). If the time gap isshorter than the time interval T_(L), it can be difficult for the MS todetermine an Rx beam for reception of the first data burst beforecompletely decoding the first PDCCH element. Therefore, the BS candetermine to use the same transmission scheme, for example, the same Txbeam and/or MIMO transmission mode as for PDCCH transmission intransmitting the first data burst and can complete scheduling of thefirst data burst in operation 1220. Additionally, the BS can determineto use the same Tx beam and/or MIMO transmission mode as for PDCCHtransmission during the time interval T_(L) after the PDCCH region.

If the time gap between the first PDCCH element and the first data burstis equal to or longer than the time interval T_(L), the BS can determinea transmission scheme for transmission of the first data burst,independently of a transmission scheme used for PDCCH transmission inoperation 1225. Specifically, the BS can determine a Tx beam and/or MIMOtransmission mode for transmission of the first data burst according toa predetermined beamforming algorithm and scheduling algorithm.

In operation 1230, the BS can determine whether to end the datascheduling. For example, in the absence of a further resource areaavailable for data transmission, the BS can determine to end the datascheduling. In an embodiment, in the absence of any more data to betransmitted, the BS can determine to end the data scheduling.

In operation 1235, the BS can transmit at least one PDCCH element in aPDCCH region and at least one data burst in a resource area indicated bythe at least one PDCCH element based on the result of the datascheduling. Specifically, if the time gap between the first PDCCHelement and the first data burst indicated by the first PDCCH element isshorter than the time interval T_(L), the BS can transmit the first databurst using the same Tx beam and MIMO transmission mode as used for thePDCCH region. If the time gap between the first PDCCH element and thefirst data burst indicated by the first PDCCH element is equal to orlonger than the time interval T_(L), the BS can transmit the first databurst using a Tx beam and a MIMO transmission mode determinedindependently of a Tx beam and a MIMO transmission mode used for thePDCCH region.

FIG. 13 is an example flowchart illustrating an operation of an MSaccording to this disclosure. The operation can support the channelstructures illustrated in FIGS. 11A and 11B.

Referring to FIG. 13, the MS can receive, from a BS, information aboutthe length of a time period during which an MS Rx beam is not changedafter a PDCCH region, that is, information about the length of a timeinterval T_(L) in operation 1305. In operation 1310, the MS can monitora PDCCH signal and can detect a PDCCH element allocated to the MS usinga first Rx beam determined for PDCCH reception in a PDCCH regionstarting from the start of a subframe. The first Rx beam can be selectedfrom among a plurality of Rx beams of the MS according to a first Txbeam and/or a first MIMO transmission mode that the BS uses for PDCCHtransmission. If the PDCCH region is jointly encoded, the MS can detectan encoding unit including the PDCCH element allocated to the MS inoperation 1310.

In operation 1315, the MS can compare the remaining time period of thesubframe after the detected PDCCH element with the time interval T_(L).If the remaining time period is shorter than the time interval T_(L),the MS can determine to receive a data signal using the same first Rxbeam as used for a PDCCH region in operation 1320.

If the remaining time period of the subframe after the detected PDCCHelement is equal to or longer than the time interval T_(L), the MS candetermine an Rx beam for the time interval T_(L) after the PDCCH regionaccording to the detected PDCCH element in operation 1330. In anembodiment, if the PDCCH element indicates a data burst occupying atleast a part of the time interval T_(L), the MS can determine to receivea data signal using the same first Rx beam as used for the PDCCH regionduring the time interval T_(L) after the PDCCH region. In an embodiment,if the PDCCH element indicates a data burst after the time intervalT_(L), the MS can receive a data signal only in an area carrying thedata burst indicated by the PDCCH element without receiving the datasignal during the time interval T_(L).

The MS can determine whether PDCCH reception has been completed, thatis, up to the end of the PDCCH region has been monitored in operation1330. If the MS has not reached the end of the PDCCH region yet, the MScan return to operation 1315. If the MS has completely monitored up tothe end of the PDCCH region, the MS can receive a data burst indicatedby the detected PDCCH element in a data region in operation 1335.Specifically, if a time gap between the detected PDCCH element and thedata burst indicated by the detected PDCCH element is shorter than thetime interval T_(L), the MS can receive the data burst using the same Rxbeam as used for the PDCCH region, that is, the first Rx beam. If thetime gap between the detected PDCCH element and the data burst indicatedby the detected PDCCH element is equal to or longer than the timeinterval T_(L), the MS can determine an Rx beam for reception of thedata burst according to a Tx scheme indicated by the detected PDCCHelement and can receive the data burst using the determined Rx beam.

In the case of joint coding of the PDCCH region, the MS can determinewhether the end of the time interval T_(L) from the end of the detectedencoding unit is before the end of the PDCCH region in operation 1315.If the end of the time interval T_(L) from the end of the detectedencoding unit is before the end of the PDCCH region, the MS can receivethe allocated data signal using an Rx beam matching to a Tx beamindicated by its PDCCH element detected from the encoding unit. If theend of the time interval T_(L) from the end of the detected encodingunit is after the end of the PDCCH region, the MS can receive the datasignal burst indicated by its PDCCH element using the same Rx beam asused for PDCCH reception. Since the MS can receive a signal using thesame Rx beam until after the time interval T_(L) from the start ofdecoding the PDCCH region, the MS can receive a signal continuouslyusing the same Rx beam until the area of the allocated data burst.

FIG. 14 is an example block diagram of a BS according to thisdisclosure.

Referring to FIG. 14, a transmitter 1420 can form one or more Tx beamsunder the control of a controller 1410 and can transmit a PDCCH signaland/or a data signal using at least one of the Tx beams. The controller1410 can generate control channel elements and data bursts to betransmitted through a transmitter 1420 and can provide the controlchannel elements and the data bursts to the transmitter 1420. Further,the controller 1410 can determine a Tx beam and a transmission schemefor transmission of the control channel elements and the data bursts andcontrols an operation of the transmitter 1420 based on the determined Txbeam and transmission scheme. Specifically, the controller 1410 candetermine a Tx beam and a transmission scheme for use in a predeterminedtime period, that is, a time interval T_(L) after a PDCCH region. Amemory 1430 can store program code and parameters used for operations ofthe controller 1410.

FIG. 15 is an example block diagram of an MS according to thisdisclosure.

Referring to FIG. 15, a receiver 1520 can form one or more Rx beamsunder the control of a controller 1510 and can receive a PDCCH signaland/or a data signal using at least one of the Rx beams. The controller1510 can recover information and data by decoding a signal receivedthrough the receiver 1520, can determine an Rx beam for use in receivingthe signal, and can control an operation of the receiver 1520 based onthe determined Rx beam. Specifically, the controller 1510 can determinean Rx beam for use in a predetermined time period, that is, a timeinterval TL after a PDCCH region according to at least one of theafore-described embodiments. A memory 1530 can store program code andparameters required for operations of the controller 1510.

The proposed method and apparatus for transmitting and receiving data ina communication system using beamforming can be implemented ascomputer-readable code in a computer-readable recording medium. Thecomputer-readable recording medium can include any kind of recordingdevice storing computer-readable data. Examples of the recording mediumcan include Read Only Memory (ROM), Random Access Memory (RAM), opticaldisk, magnetic tape, floppy disk, hard disk, non-volatile memory, andthe like, and can also include the medium that is implemented in theform of carrier waves (for example, transmission over the Internet). Inaddition, the computer-readable recording medium can be distributed overthe computer systems connected over the network, and computer-readablecodes can be stored and executed in a distributed manner.

As is apparent from the foregoing description, the efficiency of timeand frequency resources can be increased by providing a method fortransmitting and receiving data in consideration of a decoding latencyof a scheduling assignment channel allocated to an MS in a communicationsystem using beamforming.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications can be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for receiving control information anddata by a user equipment (UE) in a wireless communication systemsupporting beamforming, the method comprising: receiving, from a basestation, control information on a downlink control channel using a firstreception beam; and receiving, from the base station, data which isscheduled based on the control information, on a downlink data channelusing a second reception beam which is identical or similar to the firstreception beam, if a time interval between reception of the controlinformation and the data is less than a threshold.